Negative social interactions are a significant source of stress in early adolescence, and have been linked to emotional and behavioral problems (Rubin et al., 1998). Although not all individuals are equally vulnerable to social stress, little is known about how temperamentally based involuntary stress-reactivity interacts with volitional coping to determine risk. Further, the accuracy of the retrospective, self-report methods used in most coping research has been questioned, necessitating the use of more comprehensive assessment methods. The goals of this pilot project are to set the stage for a longitudinal investigation of relations between stress, temperament, coping, and emotional and behavioral problems in early adolescents by 1) exploring relations between self-report, adult-report, and objective measures of responses to stress, 2) comparing responses to real-world and standardized interpersonal stressors, and 3) testing coping moderated models of relations between temperament and emotional and behavioral problems. In Phase I, self-report measures of temperament, involuntary responses to stress, coping, and emotional and behavioral problems will be obtained from 450 sixth-grade students. In Phase II, 150 students and parents will participate in a laboratory study of responses to standardized interpersonal stressors, which will permit attribution of variations in responses to stress to individual differences. Confirmatory factor analyses will assess convergence of Phase II self-reports with parent and teacher reports, physiological reactivity, observational measures, and an attentional bias task. Responses to standardized laboratory stressors will be compared to responses to naturalistic interpersonal stressors. Finally, structural equation modeling will be used to test coping moderation of relations between temperament and emotional and behavioral problems in both Phase I and Phase II samples. Findings are expected to facilitate future research by guiding the selection of valid laboratory indicators of coping and responses to stress, and to contribute to the development of intervention and prevention programs tailored to the needs of individual children.